The present invention relates to a novel oxime ether, to processes for producing it, to its use as an antidote (safener) for herbicides which damage certain cultivated plants, so that such herbicides can be employed as selective herbicides, without loss of their herbicidal action against weeds, in crops of these cultivated plant. The invention relates also to compositions containing said oxime ether, optionally together with a herbicide.
It is known that herbicides of the most varied classes of substances, such as triazines, urea derivatives, carbamates, thiolcarbamates, halogenoacetanilides, halogenophenoxyacetic acids, etc., have in the case of cultivated plants an action that is not selective or insufficiently selective, with the result that these herbicides attack not only the weeds to be combatted but to a lesser or greater extent also the cultivated plants.
Various substances have already been suggested for overcoming this problem, which substances are able to specifically antagonise the harmful action of the herbicide on the cultivated plant, i.e. to protect the cultivated plant without noticeably affecting the herbicidal action on the weeds to be combatted. Depending on its properties, the antidote can be used before emergence (pre-emergence) or after emergence (post-emergence) of the plants. For example, it can be used for pretreatment of the seed of the cultivated plant (seed dressing); it can be applied into the seed furrows before sowing; it can be used for the pretreatment of cuttings; or, finally, it can be applied as a tank mixture. Furthermore, it can be employed together with the herbicide, and can be applied either by one or by several of the foregoing methods. The treatment with the antidote can be carried out before or after the herbicidal treatment, or the two treatments can be performed simultaneously. The pre-emergence treatment includes both the treatment of the cultivated area before sowing (ppi = pre plant incorporation) and the treatment of the sown cultivated area before emergence of the plants.
The suggested antidotes frequently have an action that is very specific to the species with regard to the cultivated plants (e.g. maize, cereals such as wheat, etc., rice, sorghum, soybean, cotton, sugar cane, etc.) and with regard to the type of active substance of the herbicide (triazines, carbamates, etc.) and often also with regard to the type of application (seed dressing, pre-emergence tank application, etc.); i.e. a specific antidote is frequently suitable only for a specific cultivated plant and for certain herbicidal classes of active substance.
Thus, British Patent No. 1,277,557 describes the protective treatment of seed and of shoots of wheat and sorghum with certain oxamic acid esters and amides in order to avoid the harm caused by alachlor (N-methoxymethyl-2,6-diethyl-chloroacetanilide). According to other references (German Offenlegunesschriften Nos. 1,952,910, 2,245,471 and French Patent No. 2,021,611), antidotes are suggested for the treatment of cereals, maize seed and rice seed for protection against the attack from herbicidal thiolcarmabamates. In German Patent No. 1,576,676 and U.S. Pat. No. 3,131,509, there are suggested hydroxyamino-acetanilides and hydantoins for the protection of the seed of cereals against carbamates such as isopropyl, N-phenylcarbamate, isopropyl m-chlorocarbanilate, etc. In U.S. Pat. Nos. 3,996,043 and 3,998,621, there are described certain antidotes for use with triazine herbicides which permit the herbicides to be used in cotton cultures.
The direct treatment of certain useful plants before or after emergence of the plants on a cultivated area with antidotes as antagonists of specific classes of herbicides is described in German Offenlegungsschriften Nos. 2,141,586 and 2,218,097 and in U.S. Pat. No. 3,867,444.
Whilst maize plants can be excellently protected from damage that can result from strongly herbicidally effective chloroacetanilides, such as have been described in German Offenlegungsschriften Nos. 2,212,268, 2,305,495 and 2,328,340, by an N-substituted dichloroacetamide being applied as antidote to the soil (German Offenlegungsschrift No. 2,402,983), corresponding tests in other crops, such as cultivated millet and rice, have been unsuccessful.
It is therefore a principal object of this invention to provide an antidote (safener) compound which will permit the use of chloroacetanilide herbicides, and other effective weed killers in cultivated crops, particularly sorghum and rice.